Railroads are generally constructed on a base layer of compacted, crushed stone material. A layer of gravel ballast rests on top of this stone layer. Crossties are laid in and on this ballast layer, and two parallel steel rails are attached to the crossties with fasteners. The majority of crossties in service are made of wood. Various other materials are used such as concrete, steel, and composite or recycled material in the manufacture of crossties. These alternative material crossties make up a relatively small percentage of all crossties. The crossties maintain the gage or lateral spacing of the rails. The crossties distribute the axle loads from the trains to the ballast layer below the crossties and contribute to the cushioning effect of the entire track structure. Over time, environmental factors can cause the crossties to deteriorate until they must be replaced. Annually, railroads in North America replace up to 2% or more of all wooden crossties. This constitutes several million crossties.
To manage the logistics of crosstie replacement and to quantify the need for new crossties, railroad inspectors attempt to grade the condition of crossties and the fastener system on a regular basis. This grading is most often done with a visual inspection to identify crossties and fasteners that are rotten, broken, split, or worn to an extent that their serviceable life is at its end. The process of visual inspection is quite time consuming. In practice, inspection of the track is performed by an inspector walking along the track to inspect and record the conditions of the crosstie and/or fasteners, which are spaced approximately every 20-inches along the track. One particular North American railroad reports that a crew of 3 or 4 men can grade only about 5 to 7 miles of track per day.
Devices for inspecting rail are known in the art, and software for analyzing and organizing data obtained with such devices is known in the art. For example, TieInspect® by ZETA-TECH Associates, Inc. of New Jersey is a computerized crosstie inspection system having a hand held device and software. The hand held device is used by inspectors when walking along the track and surveying the track, and the software is used to analyze and organize the data obtained with the device.
In addition to the grading of crossties, other track components must be periodically inspected for wear and deterioration. These include wear on the riding surface of the rail, integrity of anchors and fasteners, alignment of the tie plates, condition of the ballast, and gage of the rail. As with the grading of crossties, inspecting these aspects of rail can also be time consuming. Systems are known in the art for inspecting rails. For example, OmniSurveyor3D® by Omnicom Engineering of the United Kingdom is a system for surveying the infrastructure on railways. Also, ENSCO, Inc. of Minnesota provides a Laser Gage Measurement System for measuring the gage of rail using lasers.
One of the problems with laser measurement systems is that the lasers are difficult to detect in the daylight. While laser light is easy to detect at night when there are few other competing light sources, intervention is required in order to operate the lasers during daylight for the purposes of data collection of various surfaces.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above, thereby providing a system capable of inspecting surfaces during both night and day.